The present invention relates to a thin film magnetic head comprising a pair of magnetic layers; a non-magnetic layer serving as a magnetic gap and a thin film coil which are provided between the magnetic layers, and to a method of manufacturing such a thin film magnetic head.
Hitherto, a thin film magnetic head manufactured like a thin film by using various kinds of thin film forming techniques has been utilized as a magnetic head for recording signals on and reproducing signals from a magnetic recording medium, such as a magnetic tape and a magnetic disk. Such a thin film magnetic head is, for example, what is called an inductive thin-film magnetic head enabled to perform both the recording and reproducing of magnetic signals on a magnetic recording medium.
As illustrated in, for example, FIG. 5, in the inductive thin film magnetic head, a non-magnetic layer 115 formed like a thin film from a magnetic material is laminated on a lower magnetic layer 110 formed like a thin film from a magnetic material, as illustrated in, for example, FIG. 5. An insulating layer 111 is formed on the non-magnetic layer 115 by performing a high-temperature baking process on a photoresist. A thin film coil 112 is formed in this insulating layer 111 on the non-magnetic layer 115. Further, an upper magnetic layer 113 formed like a thin film from a magnetic material on the insulating layer 111. Furthermore, the lower magnetic layer 110 and the upper magnetic layer 113 are connected to each other at a winding center of the thin film coil 112, so as to constitute a magnetic core. Further, the non-magnetic layer 115 serves as a magnetic gap G of the magnetic core on a head face 114 opposing to a magnetic recording medium.
Meanwhile, when the upper magnetic layer 113 is formed in the aforementioned thin film magnetic head, a plating method, for instance, an electroplating method is used. The use of such a plating method has an advantage in that the upper magnetic layer 113 can be formed even at a slope portion indicated by a part B circled in FIG. 5 in such a manner as to have a uniform film thickness distribution.
However, in the case of forming an upper magnetic layer 113 by using the plating method, there has occurred a problem that the composition of the magnetic material becomes non-uniform in the vicinity of a magnetic gap indicated by a part C circled in FIG. 5. Thus, there have occurred other problems that the saturation magnetic flux density is lowered at this position, that consequently, the magnetic characteristics at the magnetic core are deteriorated, and that the recording and reproducing of weak magnetic signals cannot be favorably performed.
Further, when a sputtering method is used for forming the upper magnetic layer 113, the entire upper magnetic layer 113 can be formed in such a way as to have a uniform composition. The saturation magnetic flux density can be made to be uniform.
However, the sputtering method is a film forming method fundamentally having anisotropy. Therefore, this sputtering method has a drawback in that the film thickness decreases at the slope portion indicated by the circled part B in FIG. 5, as compared with that of other parts thereof. Consequently, the magnetic flux of the magnetic core at this place is saturated. This results in deterioration in the magnetic characteristics thereat.
It is therefore an object of the invention is to provide a thin film magnetic head that exhibits excellent magnetic characteristics. Another object of the invention is to provide a method of manufacturing such a thin film magnetic head.
In order to achieve the above object, according to the present invention, there is provided a thin film magnetic head, comprising:
a lower magnetic layer;
a non-magnetic layer, laminated on the lower magnetic layer;
a first upper magnetic layer, formed on the non-magnetic layer so as to form a magnetic core together with the lower magnetic layer and the non-magnetic layer, the first upper magnetic layer having a first saturation magnetic flux density and a first magnetostriction constant;
an insulation layer, formed on the non-magnetic layer;
a thin film coil, provided in the insulation layer; and
a second upper magnetic layer, formed on the insulation layer so as to be at least above the thin film coil, the second upper magnetic layer having a second saturation magnetic flux density and a second magnetostriction constant,
wherein the first saturation magnetic flux density is higher than the second saturation magnetic flux density, and the second magnetostriction constant is lower than the first magnetostriction constant.
According to the present invention, there is also provided a method of manufacturing a thin film magnetic head, comprising the steps of:
providing a lower magnetic layer;
laminating a non-magnetic layer on the lower magnetic layer;
forming a first upper magnetic layer on the non-magnetic layer while performing spattering process;
forming an insulation layer on the non-magnetic layer while providing a thin film coil therein; and
forming a second upper magnetic layer on the insulation layer so as to be at least above the thin film coil, while performing plating process.
In the above configurations, the first upper magnetic layer placed in the vicinity of a magnetic gap of the magnetic core can be formed from a magnetic material exhibiting a relatively high saturation magnetic flux density. On the other hand, a second upper magnetic layer placed just above the thin film coil can be formed from a magnetic material exhibiting relatively low magnetostriction property. Thus, a favorable magnetic flux flow in the magnetic core can be ensured. Moreover, the magnetic core located at a place in the proximity of the magnetic gap can be formed with high dimension accuracy.
Therefore, the recording and reproducing of weak magnetic signals can be efficiently performed with high accuracy.